Floating rib injuries are caused, in part, by a vulnerability in human anatomy. The rib cage, which is made up of 12 pairs of ribs, doesn't fully attach to other bones in the same way at all points.

Pain under the left rib cage can be a sign of a heart attack, which is a medical emergency. An enlarged or ruptured spleen, which may result from trauma, can cause sharp pain. Kidney infections can ...